Preparation, phase formation and photoluminescence properties of ZnO–SiO2–B2O3 glasses with different ZnO/B2O3 ratios

Glasses in ZnO–SiO2–B2O3 ternary system with different ZnO/B2O3 ratios were studied as scintillating materials. Differential thermal analysis and X-ray diffraction patterns showed that nucleation of willemite and zinc oxide was considerably facilitated with increasing the ZnO/B2O3 ratio. Photoluminescence spectra showed a reduction in intensity over the UV region upon this increment prior to the formation of crystalline phases. Optical basicity as a measure of nonbridging oxygens (NBOs) is elaborated in this study as a major cause of this effect. However, near band edge emission (NBE) after crystallization implied an increase in intensity upon the increment of the ZnO/B2O3 ratio which proved the key role of willemite and zinc oxide as UV emission centers.

► Embedding ZnO in glass, increases UV emission by eliminating the visible band.
► Increasing the ZnO/B2O3 ratio facilitated precipitation of Zn-rich crystals.
► The larger the number of NBOs, the less intensive is the UV emission band.
► Increasing the ZnO/B2O3 ratio led to an increase in the UV emission band.
► Zn-rich crystals are responsible for the PL emission band over the UV region.